This invention relates to apparatus of the type having a pair of substantially parallel journaled rolls that are spaced by a gap, for example rotary die cutting equipment, and in particular to a bearing cooling system for such apparatus for maintaining the gap size substantially constant.
Many different types of apparatus employ a pair of rolls that are journaled substantially parallel to each other and separated by a gap, for example rotary die cutting equipment. In some of these apparatus, the gap size is critical, and thus maintaining this gap size is important. However, for a number of reasons the gap size can vary during use of the apparatus. A significant contributor to the variance in the gap size is thermal expansion of the apparatus from heat generated by the turning of the rolls. Some of the heat is generated by the forces and friction on the gears driving the rolls. Some of the heat is generated by forces on the bearings in which the rolls are journaled (including pre-loading), and bearing resistance and friction. Controlling the heat generated by the turning of the rolls would reduce the thermal expansion of the apparatus and help maintain the gap size substantially constant.